1. Field of the Invention
The present invention relates to a plate-link chain, in particular a chain for a motor vehicle drive system. The link plates are configured in such a way as to prevent incorrect assembly of the chain.
2. Description of the Related Art
Known motor vehicle drive chains include a large number of link plates that are hingedly connected with each other by rocker members that extend transversely to the longitudinal direction of the plate-link chain. The rocker members are positioned in openings provided in the link plates. There are curved-shaped contact surfaces located on the rocker members and on the link plates, along which contact surfaces the rocker members and link plates are in contact with each other to transmit power. The rocker members also include curved-shaped rolling surfaces, along which the rocker members roll on each other to transmit power. The rocker members are shaped asymmetrically in the height direction of the rocker members, in a cross section extending in the longitudinal direction of the plate-link chain, and the contact surfaces between rocker member and link plate are provided on upper and lower contact surface regions in the height direction of the rocker member.
Such a plate-link chain can be a toothed chain, which can be installed in a power divider transmission of a motor vehicle, for example, or as a drive chain for an auxiliary unit of an internal combustion engine of the motor vehicle. In those cases the plate-link chain is designed as a toothed chain, and transmits tractive force between a driving and a driven sprocket wheel. However, a plate-link chain such as the type identified at the outset can also be installed as a means of transmitting tractive force in a belt-driven conical-pulley transmission, or the like, for example, and can there transmit the tractive force by means of frictional contact between the rocker members and the conical disk surfaces of the two conical disk pairs.
In previously known plate-link chains, symmetrical pressure pieces—also called rocker pressure pieces—were used, which were positioned in openings in the link plates. Those known rocker members are symmetrical about a plane of symmetry that divides the rocker members into upper and lower halves. As a result of that configuration, a distance from the inner peripheral edge of the opening receiving the rocker members to an outer peripheral edge of the link plate, in the region of the lower bow lying opposite an upper bow of the link plate, becomes minimal, and thus the cross sectional area available for transmitting power becomes minimal. That design therefore results in a concentration of stress in that region between the opening of the link plate and the edge of the link plate, which reduces the service life and the transmitting capacity of the link plate, and thus of the entire plate-link chain.
To counter that problem, a plate-link chain has already become known on the basis of unpublished German patent application DE 10 2005 054 714.1, owned by the assignee of the present application. That chain has asymmetrical rocker members in the direction of the rocker member height, and it thereby ensures that the working part stresses that arise between rocker member and link plate in the upper and lower contact surface regions are significantly reduced, so that the service life of the plate-link chain increases.
Those asymmetrical rocker members are also inserted into openings of the link plates, which must be done in such a manner that the rolling surfaces of the rocker members are associated with each other. Furthermore, the asymmetrical rocker members must be inserted into the openings with their positions oriented so that the openings are broader-shaped in the regions corresponding to the broader upper parts of the rocker members. As already mentioned earlier, care must be taken to ensure that the asymmetrical rocker members are inserted into the openings in the link plates with their positions properly oriented with respect to each other.
Accordingly, an object of the present invention is to improve the plate-link chain so that a situation where the rocker members are installed incorrectly in the link plates is not possible.